registration: Load extra autoload files before executing callbacks

registration: Load extra autoload files before executing callbacks

Callbacks should be able to safely assume that anything (or at least mostly)
defined in extension registration is already loaded and processed when
the callback itself is executed. To make sure, that this applies, callbacks
should be executed after all extra autoload paths are loaded.

Bug: T131978
Change-Id: I2c6624423957a8a00523b126fa7209d9c283aa9e